The southern margin of Flemish Cap, offshore Newfoundland: Processing and interpretation of seismological data provide insights into the rifting evolution.

摘要

The Newfoundland/Iberia conjugate continental margins developed during Jurassic and Cretaceous time. They are good places to study rifted margins since they are non-volcanic, so that extensional crustal structures are not altered or obscured by magmatic processes. The "ERABLE" seismic reflection survey was recorded in the Newfoundland basin by the Geological Survey of Canada and IFREMER in 1992. I have processed and interpreted three ERABLE profiles extending from the southern margin of Flemish Cap extending into the Newfoundland Basin. Various types of noise such as multiples and side scattered reflections posed challenges for producing a seismic section that represents subsurface reflectivity. F-k and radon filters improve the signal to noise ratio in deep water, but were less successful in the shelf region of the Flemish Cap.;The final processed lines have provided a more comprehensive data coverage along the southern margin of Flemish Cap. Combining these data with SCREECH seismic profiles, two ODP drill sites, and other geophysical data have allowed the mapping of distinct zones of continental, transitional, and oceanic crust in this region. I compare these results to crustal boundaries on the Iberia margin that are well constrained from detailed seismic and drilling.;My results indicate asymmetry in the conjugate pair, with the zone of extended continental crust and transitional crust being much wider on the Iberian margin compared to the Newfoundland margin. Also, there is evidence of possible detachment faulting on both margins, although less wide spread on the Newfoundland margin. I propose either a simple shear or simple shear/pure shear combination model involving a westward dipping detachment fault, with the Newfoundland margin acting as the upper plate.;However, the Newfoundland margin has a long and complex rifting history that cannot be explained by only 2-D rifting models, thus a Late Jurassic to Early Cretaceous rifting and break-up model is presented as an attempt to account for the present day structure of the southern margin of Flemish Cap.